Urarte Rodríguez, Estíbaliz

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https://academica-e.unavarra.es/handle/2454/50105

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Urarte Rodríguez

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Estíbaliz

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Ciencias del Medio Natural

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750608

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9697

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2014 - 20162
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Author: Esteban Terradillos, Raquel × End date: 2019 ×

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Now showing 1 - 2 of 2
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    PublicationOpen Access
    Both free indole-3-acetic acid and photosynthetic performance are important players in the response of Medicago truncatula to urea and ammonium nutrition under axenic conditions
    (Frontiers Media, 2016) Esteban Terradillos, Raquel; Royo Castillejo, Beatriz; Urarte Rodríguez, Estíbaliz; Zamarreño, Ángel M.; García Mina, José M.; Morán Juez, José Fernando; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
    We aimed to identify the early stress response and plant performance of Medicago truncatula growing in axenic medium with ammonium or urea as the sole source of nitrogen, with respect to nitrate-based nutrition. Biomass measurements, auxin content analyses, root system architecture (RSA) response analyses, and physiological parameters were determined. Both ammonium and ureic nutrition severely affected the RSA, resulting in changes in the main elongation rate, lateral root development, and insert position from the root base. The auxin content decreased in both urea- and ammonium-treated roots; however, only the ammonium-treated plants were affected at the shoot level. The analysis of chlorophyll a fluorescence transients showed that ammonium affected photosystem II, but urea did not impair photosynthetic activity. Superoxide dismutase isoenzymes in the plastids were moderately affected by urea and ammonium in the roots. Overall, our results showed that low N doses from different sources had no remarkable effects on M. truncatula, with the exception of the differential phenotypic root response. High doses of both ammonium and urea caused great changes in plant length, auxin contents and physiological measurements. Interesting correlations were found between the shoot auxin pool and both plant length and the “performance index” parameter, which is obtained from measurements of the kinetics of chlorophyll a fluorescence. Taken together, these data demonstrate that both the indole-3-acetic acid pool and performance index are important components of the response of M. truncatula under ammonium or urea as the sole N source.
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    PublicationOpen Access
    Established and proposed roles of xanthine oxidoreductase in oxidative and reductive pathways in plants
    (Springer, 2014) Urarte Rodríguez, Estíbaliz; Esteban Terradillos, Raquel; Morán Juez, José Fernando; Bittner, Florian; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
    Xanthine oxidoreductase (XOR) is among the most-intensively studied enzymes known to participate in the consumption of oxygen in cells. However, it attracted the attention of researchers due its participation in free radical production in vivo, mainly through the production of superoxide radicals. In plants, XOR is a key enzyme in purine degradation where it catalyzes the oxidation of hypoxanthine to xanthine and of xanthine to uric acid. Both reactions are accompanied by electron transfer to either NAD+ with simultaneous formation of NADH or to molecular oxygen, which results in formation of superoxides. Characterization of plant XOR mutants and isolated XOR proteins from various plant species provided evidence that the enzyme plays significant roles in plant growth, leaf senescence, fruit size, synthesis of nitrogen storage compounds, and plant-pathogen interactions. Moreover, the ability of XOR to carry out redox reactions as NADH oxidase and to produce reactive oxygen species and nitric oxide, together with a possible complementary role in abscisic acid synthesis have raised further attention on the importance of this enzyme. Based on these established and proposed functions, XOR is discussed as regulator of different processes of interest in plant biology and agriculture.